Junction-box for electrical conductors.



C. W. DAVIS.

JUNCTION BOX FOR ELECTRICAL CONDUCTORS.

APPLICATION IILED MAR. 24, 1909.

1,093,607. Patented Apr. 21, 19m

3 SHEETS-SHEET 1.

WITNESSES:

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C. W. DAVIS.

JUNCTION BOX FOR ELECTRICAL CONDUCTORS.

APPLICATION FILED MAR. 24, 1909.

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Patented Apr. 21, 191i 8 SHEETS-SHEET 2.

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U. W. DAVIS.

JUNCTION BOX FOR ELECTRICAL CONDUCTOBS.

APPLICATION FILED MAR.24,1909.

1,093,607, Patented Apr. 21, 1914.

3 SHEETS-SHEET 3.

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UNITED STATES PATENT OFFICE.

CHARLES W. DAVIS, 01? EDGEWORTH, PENNSYLVANIA, ASSIGNOR TO STANDARDUNDERGROUND CABLE COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORA- TIONOF PENNSYLVANIA.

JUNCTION-BOX FOR ELECTRICAL CONDUCTORS.

in assembling, compactness, efliciency and durability, and many specificpractical advantages which will be apparent to one familiar with thisart.

My invention is illustrated in the accompanying drawings.

Figure 1 is a view partlyin elevation, partly in central verticalsection of my improved junction box; Fig. 2 is a plan view of the samestructure; Figs. 3 and 4 are views in perspective of detached details;Figs. 5 and 6 are views similar to Fig. 1, illustrating certainmodifications; Fig. 7 is a view in perspective of a structural detail.

-The same numerals are used throughout to designate parts which reappearin the several figures.

The particular kind of junction box with which I am here primarilyconcerned is what may be termed a distributing box; that is, one withinwhich the current car ried by a supply cable is distributed and led outthrough a plurality of independent lines. Within such a unction box thecontacts are ordinarily made through fuses, a well-known safety devicein all such work. In certain details my improvements have a more generalapplication, as I shall hereinafter show, but primarily all have to dowith such a current distributing junction box.

The junction box shown in Figs 1 and 2 is cylindrical, with a detachablecover plate 2, which when applied may be bolted in place, the jointbeing packed to prevent the ingress of moisture, in well-known manner.The bottom of this cylindrical junction box is of somewhat irregularform, its symmetry being broken by orifices 3, formed for the leading inand out of the conductors, and by inwardly extending supports t tosustain in proper position the contained parts.

Specification of Letters Patent.

Application filed March 24, 1909.

Patented Apr. 21, 1914;.

Serial No. 485,476.

WVithin the box is a plate 5 which carries the contacts and is in turncarried by the supports 4. This plate 5 is preferably formed wholly ofinsulating material, such as slate or porcelain; but it is onlyessential that it be of insulating material in such parts as to preventleakage of the currents carried. Secured in the upper face of plate 5are the contacts for the opposite terminals ofa series of cartridgefuses 6, and beneath the plate these contacts are at one end united witha series of bus-bars 7, and at the opposite end provision is made foruniting the incoming' and outgoing 00nductors. The particulararrangement of these cartridge fuses and their contact pieces upon theplate 5 is a feature of invention. I dispose the cartridge fuses (whichare preferably cylindrical bodies) radially about the center of the box;the contacts for the inner ends are knife-blade contacts, 'a knifeblade8 being formed at one end of the cartridge fuse. The contacts for theouter ends of these cartridge fuses are the yoke contacts illustrated;electric continuity being had in this case not through a longitudinalprolongation of the structure, but through contact plates 9, built outlaterally on the outer ends of the cartridge. fuses.

In both cases the members carried by the plate 5 to engage the cartridgefuses make binding contact by spring pressure, as is usual in suchstructures. By such radial arrangement of the fuses and such specificforms of contact, I economize space, employ fuses of relatively greatcubical contents within a relatively small space, and obtain a compactand simple structure.

It will be observed in examining Figs. 1, 3 and 4 that the plate 5extends out to the cylindrical wall 1 of the junction box, and, but forthe peripheral recesses provided for making the contacts, covers overand incloses a chamber formed between the supporting flange at and theouter wall of the box-a chamber into which the orifices 3 open. Fromwithin this chamber the incoming and outleading conductors will beplaced in connection with the fuse contacts. When this has been done, itwill be good practice to fill the chamber with an insulating substancesuch as is ordinarily applied in'fiuid state; and for such insulation soapplied my structure is peculiarly adapted. Ordinarily in suchinstallations, where a filling of insulation is introduced, any extendedsurface of the insulation is a point of weakness, for 5 dust collectingupon such surface is'apt'to provide a leakage path for the flowingcurrent; but in this case, the chamber thus filled being substantiallyclosed above, and

the insulating compound being applied to fill the whole chamber, thesurface upon which dust might otherwise collect is restricted, and thesecurity of the box against leakage is increased to a correspondingdegree. While I have, spoken of this peripheral space as a singlechamber, I preferably divide itby partitions 24 into as manyseparatechambers as there are peripheral ori-.

fices. In high voltage work it may be de- -sirable to fill the centralspacealso, within the walls 4 and beneathplate,5 in which the bus-bars7'lie, with insulating compound. Thebox illustrated,in:;-Figs. ,1 and 2is ofrthe outward leading orservice cables also contains'threeindependentzconductors and a neutral; I 1 ill}; order= toiadistributethe current of the gfeeding cable conductorsto like phase conductorsoftheiservice ,cables the plate 5 40 carries-twelve distinchlines ofcurrent flow through twelveindependent g-cartridge fuses.

These twelve gcartridgeafuses, arranged in:

groups of three, each connected at theirlouter ends to one ofztheaconductorsof -the cable,

while theinnerf contacts Ofi the itwelve fuses;

are connected to the bus-bars 7 one from each of the four groups offuses being connected to one of the three busbars 7 The neutralastrand10 of eachcable is secured to a bind-- ing post in the wall of the box.Thus it. will be seen that the current of each independent conductorof-the feeding vcable may be sub divided in the-junction .box and ledontin three divergentlines; And it .willbe 'un derstood from this detailedexplanation that my arrangement of orifices, bus-bars, and cartridgefuses permits ,of rearrangement and combination to unlimited extent tomeet particular conditions.

For convenience in amembling and repairs, I preferably divide the plate5 into as many sector-shaped parts as there are orifices 3, that eachpart with its own cartridge fuses maybe independently removed to giveaccess toany one of the orifices and any one zingmaterial extendsbetween the binding of the cables without disturbing th e others. Asillustrated in Fig. 2, one of the four sector-shaped divisions of plate5 has been removed; 'How ever, that when desired a'l-l of 'the plate 5ivith its contacts may be removed together, I preferably provide a ringlike member 11, resting. immediately upon the support 4 and hearing inturn the divided plate 5. It is with like purpose that the peripheralchamber beneath plate 5 is subdivided by thevpartitions 24that eachcable end may be independently accessible. The modification shown inFig. 5 consists in the arrangement of all the cable orifices in thelower head of the cylindrical box,- and 30 in providing a centralorifice for the feeding cable and peripheral orifices for the outward.

leading cables. In this arrangement itwill be understoodthat thedirectionpf theflow of. current-through;- the cartridge fuses is fromthe center of the junction box toits periphery, and. that the. chamberwithin which-the incoming conductors may. ;be. im-

mersed' in insulating compound, beneath ,a

covering plate, is a centrally arrangedcham- 9o berand not aperipheral-one. 1 The leads-out. "however mayalso be immersed ininsulating compound, applied to fill .the peripheral space outsideofethe supporting Wall-4 and beneath plate 5. 7 are bus-bars; theyiqhavecentral circular openings where connection is lIiadeWltlIIhB feeding-inconductors. f 5;;

In Fig.6 a further modificationds showm;

The orifices are all jperipheral as inthe box of F ,ig. 'f.1, but ,thearrangement-is such that the c onducto rs of ;.the. connecting cablesare;

carried to the.center,and the,bus bars are; arranged to; be connectedwith the: outer ends .of the. cartridge ,fuses and are inclosed in achamber'forrned by.;a peripheral trough-v shaped casting 20 carried upontheisupports 4c and closed above' by the plate 5. .It'will'be observed;that in'thiscase the plate j5v is carried upon :the E trough l 20 whichi in turn rests uponvthe supports 4:. Further, ..-there is here, acentral circular. orifice through plate 5, and within this orificeisa'small plate 27, (.in effect a continuation: of plate 5), convenientlycarried on Vajpost 22 secured in the bottom. of the box. The plate'11527 carries binding posts 21 forthe neutral lines of the .cables. Inthisiboxthe cable strands or conductors ,which carry the supply currentsare sweated into bushings carried on the ends of conductors 25 which areelectrically united with the springjacks for the knife-blades of theinner ends of the cartridge fuses, and the neutral strands are sweatcdinto bushings carried on the ends of conductors 26 carried in plate 27.These conductors 26 may conveniently be continued in binding posts 21above plate 27, and the individual binding posts connected together. Toprevent leakage, a screen 23 of insulatposts 27 and the spring-jacks forthe inner ends of the cartridge fuses. It will be ap parent that in thespace beneath plates 5 and 27 in the box of Fig. 6 insulating compoundmay be applied to any desired depth. In high voltage work it may bedesirable to fill the trough containing the bus-bars 7 with insulatingcompound.

In Figs. 1 and 2 I have shown certain improvements in means forintroducing an armored, lead sheathed cable into the junction box. Anarmored cable is the ordinary leadsheathed cable with an outer coveringof steel ribbon wound upon it toafford protection against injury to therelatively soft body within. In connecting up such a cable with thejunction box, the armor covering must first be stripped away, then thelead sheath, then the insulation, and finally the contained conductorsare laid bare and the desired connections made. The lead sheath must besecured in the orifice in the wall of the box. It is old practice tocarry the sheathed cable through a closely fitting orifice and runsolder in the joint; but such a joint is insecure; and a better way isto secure a bushing or thimble in the orifice and when thesheathed cableis threaded in to make a wiped solder joint upon thimble and cablesheath.

Having regard now'to the particular construction' shown in Fig. 1,the'proper way of assembling is to introduce the end of the cable(previously prepared) through the orifice-in the wall of the junctionbox and to make the electrical connections within; then, drawing theprotruding cable out ward, to take up the slack, and thus bring-- ingthe parts to position, to make the wiped solder joint 13 upon thebushing 12 in the orifice and the cable sheath. A practical difficultywith this seemingly simple procedure is that it is almost impossible tomake a wiped solder joint upon an ordinary thimble so inserted becausethe heat is con ducted away so rapidly into the body of the structure.Accordingly, I employ a bushing of two metals; having a body portion 28of such hardness (as copper or bronze) as to be properly secured in theorifice 3, and an extension 29 of such low heat conductivity (as lead)as to afford a proper base for the joint; This particular constructionis described in detail in my Patent No. 1,061,527, and also in myco-pending' application, filed February 15, 1913, Serial No. 748,720,which is a division of my present application. I here describe mypreferred mode of making such a bi-metallic thimble, for it is new withme, and is practically valuable. The annulus of soft metal 29 is seated(as may be seen in Fig. 1 of the drawings,) in an annular groove orchannel in the harder body portion 28. These two parts are first formedindependently. The body portion is sustained in position withthe grooveuppermost, heated to a suificient degree, and mol ten solder introducedin the groove. The annulus of soft metal is then applied, immersededge-wise in the solder bath. The parts then cool and harden to a securestructure, efficient for the purpose, and may be conveniently applied inthe orifice 3 by the screw-thread connection shown.

The lead cable sheath is secured in the manner I have described. With anarmored cable, the steel covering, cut away to lay bare the lead sheath,may in practice, if left without support,cause a drag and a pullingstrain upon the joint, such as it is desirable to avoid. In order toproperly secure this armor coverin and relieve the joint from strain, Iprovi e a clamp, preferably consisting of two members 14, with serratedor corrugatedinner surfaces substantially surroundingand inclosing thearmored cable adjacent to the point where the armor covering is cutaway.These clamping members engage also the body of the box itself, as bya'flange' 15' around orifice 3 and engagingrecesseslG formed within theclamping members; Bolts 17 may be provided to draw the clamping members14 together and in so doing to firmly grasp the armored cable, while theengaging flanges between the clamping members and the walls of the boxhold the'whole rigid.

In Fig. 7 I have shown an improvement in knife-edge contacts, which,while not limited to this particular service, I find applicable to thecontacts for the cartridge fuses in the junction box I have hereindescribed. A difiiculty with the knife-blade contact as usually made isthat the contact surfaces are apt to be more or less discontinuous, thearea of actual contact is apt to be more limited in extent than thestructure is designed to afford. This is due to unevenness of surfaces,corrosion, insufiiciency of spring pressure, and the like. As contrastedwith the knife-blade contact, one made by bolting the surfaces togetheris more efiicient in that a large area of actual contact can withgreater certainty be obtained. As shown in the figure alluded to, Isupplement the spring-contact of the spring-jack and knife-blade with abolt 18 passing through and clamping the whole. Instead of having botharms of the springjack resilient (though that familiar construction mayif desired be employed), I preferably make one arm unyielding and theother yieldin and bolt through with a set screw from t e yielding arminto the unyielding one. This detail is preferable because of facilityin assembling. I further preferably provide, to the end that theclamping pressure of the bolt may be most efiectively distributed, afollower plate 19 of extended area between the head of the bolt and theresilient arm of the spring-jack.

3o; verse 'partitiominto central and peripheral chambers, substantiallyas described.

The knife-blade contact is made in the usual manner, in that thespring-jack is spread by the knife-blade as it comes into place, and soan immediate contact of some con siderable extent is effected evenbefore the bolt is tightened. This is desirable for practical reasons.The yielding arm of the spring-jack is perforated to allow the passageof the bolt, and the knife blade is preferably cut away farther, as isindicated at 20, to allow the blade to come to its seat while the boltis inserted.

The installation of this junction box, and the introduction of theconductors, and arrangement of theecntained parts, are, I believe,clearly disclosed in the foregoing descriptionf Certain features of theform of box illustrated in Fig.6 are described and claimed in mydivisional application Serial No. 741,574, filed January 11, 1913.

I claimas my invention:

1. In a junction-box structure, the combination ofla casing, providedinternally with a partition wall extending from the bottom of the casingand affording support for a removable transversely extending partition,said supporting wall dividing the space within casing and beneath saidtrans- 2. In a junction-box structure, the combination .ofacasing,-provide d internally with partition walls extendingfrom thebottom of the casing and affording support for a removabletransverselyextending partition, said supporting walls dividing the space within tle casing and beneath said transverse partition into a central chamberand a plurality of peripheral chambers, substan tially as described. a.v

3..,In a junction-box structure the combination of a casing ofsubstantially circular contour and provided internally with circular andradial partition walls extending from the bottom of the casing andaflording support for a removable transversely-extending partition, saidsupporting walls dividing the spacewithin .the casing and beneath saidtransverse partition into a central substantially circular chamber and aplurality of peripheral sector-shaped chambers, said transversepartition composed of a plurality of sector-shaped parts, each coveringone of said peripheral chambers, and orifices in the wall of said casingopening one into each of said peripheral cham bers, substantially asdescribed.

4. In a junction-box structure, the combination of a casing, providedinternally with a partition wall extending from the bottom of the casingand afl'ordingsuppoit for a removable transversely extending partitionof insulating material, and a 'pair of binding posts extending throughsaid transverse partition one on either side of said partition wall,substantially as described.

5. In a junction-box structure for electrical cables, at collocation ofcartridge fuses arranged in substantially radial position about acenter, eachindividual fuse being provided at its inner end with aknife-blade contact, and at its outer end with a yoke contact,substantially as described.

(3. In a junction-box structure, the combination of a casing, a plateextending trans:

\ersely within said casing, a plurality of orifices opening through thewall of said casing and into the chamber beneath said. plate transverseplate, said transverse formed of a plurality of separately removablesections corresponding in number and in position to said openings,substantially as described.

7. In a junction-box structure, the combination of a casing, a supportor carrier removably seated Within said casing and sus-' taining apartition plate which when the parts are assembled extendstransversely-1 within said casing, a plurality of cable 0r1-:

fices opening through the walls of said casing to the chamber beneathsaid plate, said plate being composed of a plurality of sepa ratelyremovable parts or sections corre-. sponding in number and position tosaid cable orifices, substantially as described.

8. In a junction-box structure for a plurality of niultiple-conductorelectrical Leas, plurality; of

bles, a casing provided with a orifices for the introduction of anumberzof cables, a plurality of separately detachable plates mountedwithin the casing and corre-: sponding in niunber to the cables to ,bein of bus-barsinounted within the casing, and in number'corre-- thecurrent-delivering conductors of the cables to be introduced, each. of,being equipped with troduced. a plurality sponding to the aforesaidplates contact pieces for the opposite a plurality of cartridgeterminals of connection with said several bus-bars,-substantially asdescribed.

9. In a junction-box structure forelectrical cables, a. casing with aplurality of de-.

and when in place therein covering over and substantially closing of?and dividing fuses, the number: thereof corresponding with the numberiof current-delivering conductors of the cables; to be introduced, thecontact pieces for-one. set of terminalsbeing adapted to be sev--:orally placed in electrical connection with, the conductors of onecable, and thecontact. pieces for the opposite set of. terminals.adapted to be severally placed in electrical such depressions orrecesses from the remay be electrically connected, substantially mainderof the chamber Within the casing as described. 10 and forming acorresponding number of In testimony whereof, I have hereunto separablyfillable and drainable chambers set my hand.

for insulating compound, said plate being CHARLES W. DAVIS. providedwith contact pieces With which \Vitnesses:

conductors of the cables introduced through CHARLES BARNETT,

the said orifices in the Wall of the casing J. HERBERT BRADLEY.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, D. C.

